Extreme pressure lubricating oil additive

ABSTRACT

A thio bis(dialkylphenol), wherein the alkyl substituents are C1-C20 groups with the proviso that the total number of substituent carbon atoms is at least 10, is found to be a superior extreme pressure additive.

[451 Oct. 29, 1974 EXTREME PRESSURE LUBRICATING 01L ADDHTIVE [75] Inventor: Brian R. Kennedy, San Rafael,

Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: Nov. 20, 1972 [21] Appl. No.: 308,227

[52] US. Cl 252/481, 260/609 F [51] int. Cl Cl0m 1/42 [58] Field of Search 252/482, 609 F [56] References Cited UNITED STATES PATENTS 8/1941 Cantrell et al. 252/482 X 2,370,756 3/1945 Sibley 252/482 X 3,114,713 12/1963 Coffield. 252/482 3,442,806 5/1969 ONeill 252/482 X Primary Examiner--W. Cannon Attorney, Agent, or FirmG. F. Magdeburger; C. J. Tonkin; S. R. La Paglia [5 7] ABSTRACT A thio bis(dialkylphenol), wherein the alkyl substituents are C -C groups with the proviso that the total number of substituent carbon atoms is at least 10, is found to be a superior extreme pressure additive.

2 Claims, N0 Drawings EXTREME PRESSURE LUBRICATING OIL ADDITIVE BACKGROUND OF THE INVENTION 1. Field of the Invention A lubricating oil performs several functions related to the lubrication of metallic surfaces which requires the oil to act as a carrier of functional additives such as dispersants, detergents, extreme pressure agents, viscosity index improvers, etc. There are few commercial examples of an ashless extreme pressure agent. Such an additive is of importance in formulating industrial greases and oils for internal combustion engines operating on unleaded fuels. The purposeof this work was to develop such an ashless additive. Extreme pressure agents also find use in functional fluids and fuels. Dialkyl-substituted phenols wherein the alkyl must be branched at the alpha-carbon atom (so-called hindered" phenols) and wherein the thio bridge is para, e.g., 4,4'-thio bis( 2,6-ditert-butylphenol), are known in the prior art as antioxidant additives. U.S. Pat. Nos. 3,326,800 and 3,250,712.

SUMMARY OF THE INVENTION A thio bis(dialkylphenol which is preferably monoor dithio ortho-bridged and in which the alkyl groups are C C, with the proviso that the total number of substituent carbon atoms is at least l0,'functions as a superior extreme pressure additive. The additive is, for example. the reaction product of an alkylated cresol, preferably an o-cresol, with sulfur monochloride.

DETAILED DESCRIPTION OF THE INVENTION Lubricating oil, fuel and functional fluid additives which function as extreme pressure agents are prepared from the reaction of a dialkylated phenol with sulfur monochloride.

It is an essential feature of the invention that the phenol be (ii-substituted with C1-C alkyl groups, such that the total number of carbons substituted on the phenol is at least 10. It is preferred that one of the alkyl groups is ortho to the phenolic hydroxy group and the other alkyl is para. The presence of ortho alkyl substituents, or ortho-para substituents reduces the probability of other than the ortho-bridged bis structures in the sulfurized product.

The sulfurization is preferably performed with sulfur monochloride, S Cl but other sulfurizing agentsmay be utilized. The product has a structural formula:

nonyl phenol, methyl dodecyl phenol, dipentyl phenol, ethyl undecyl phenol, propyl decyl phenol, butyl nonyl phenol, amyl octyl phenol, hexyl heptyl phenol, methyl polypropenyl phenol, ethyl polyisobutenyl phenol, ditetrapropenyl phenol, etc.

The value of n can be 1.-4, more usually in the range of l to 2 and the disulfide is particularly preferred. The weight percent of sulfur is preferably within the range of from 5 to 30 percent and most preferably in the range of 5 to 10 percent. 1

Various methods of preparing sulfurized alkyl phenols are known in the art. The particular method employed is not critical to this invention, although some methods will be favored over others by providing higher weight percents of sulfur. U.S. Pat. No. 2,409,687 describes a method of sulfurizing using sulfur monochloride and the alkylphenol in an inert solvent. U.S. Pat. No. 2,680,096 and 3,178,368 describe sulfurizing using sulfur with calcium phenoxide in the presence of ethylene glycol.

Depending on the method of sulfurization, various solvents or dispersants may be used. Illustrative of such solvents are oil, particularly hydrocarbonaceous fluids used as lubricating oils, inert hydrocarbons, both aromatic and aliphatic, etcetera. The concentration of the reactants may be varied widely. In sulfurizing with sulfur, the weight ratio of sulfur to alkylphenol will be in the range of 1:0.9-10, usually about 1:2-6. Elevated temperatures will be used, the degree depending on the particular reactants. Generally, temperatures for sul furization with sulfur will be in the range of about 200 to 350F.: In sulfurization with sulfur monochloride, the reaction mixture will be refluxed with stirring and the sulfurmonochloride will be slowly added as illustrated in the following examples.

Example 1: Alkylation of o-cresol with propylene tetramer Y o-cresol (540 grams), propylene tetramer 840 grams), and clay catalyst grams) were placed in a 2-liter flask equipped with stirrer, reflux condenser, and thermometer. The stirred mixture was heated at 150C i 6C for 3 hours, cooled, and filtered. The filtrate was stripped at l 10C and 8 mm. vacuum to give tetrapropenyl o-cresol (899 grams). Hydroxyl number, 192 mg KOH/g; equivalent weight, 292; calculated for C19H32O, 276.

Example 2: Sulfurization of Tetrapropenyl o-Cresol Tetrapropenyl o-cresol (898 grams) was taken up in n-heptane (800 ml.). To the solution was added sulfur 'monochloride (80.4 ml., grams) with stirring during 1 /2 hours. The stirred solution was heated under reflux for 2 hours, cooled to 80C, and 1,000 ml. of water was added. The heptane layer was separated, washed with water (three times at 1,000 ml.), and dried with Na SO Evaporation gave the sulfurized phenol (758 grams); percent CI, 0.67 percent by weight.

Example 3:

234 grams of substantially dipentylated phenol was diluted with n-heptane (500 ml.) and sulfurmonochloride (80.4 ml., 135 grams, about 1 mol) wasadded dropwise with stirring during 2 hours. The stirred solution was heated underreflex with a nitrogen purge for 2 hours, cooled, and 400 ml. of water was added. After stirring for another hour the heptane layer was separated, washed with water (10 times at 500 ml.), and dried with Na SO Evaporation gave the sulfurized phenol (218 grams);percent chlorine, 0.21 percent. Example 4:.Alkylation of p-tetrapropenyl phenol with C -C olefin To the mono substituted phenol (352.7 grams), and shaft. The load at failure in pounds is taken as a quanti- C7-C,, alpha olefins (165.7 grams) was added clay catatative measure of the EP property of the oil composilyst (35 grams). The stirred mixture was heated under tion. Mineral oils in general will fail at 600-900 reflux at 135C for 2 hours, cooled to 100, and filpounds. Oils with moderate EP additives will fail at tered. The filtrate was stripped at 120C and 8 mm. 5 2900-1590 P01111015 y Fffeclive extreme P vacuum to give the diarkylmed pheno] 3 grams); sure additives will permit loadings in excess of 3,000 droxyl number, 139 mg KOH/g; equivalent weight, Rounds The extrem? P P QW of the calculated for CWHMOI equivalent weightI 4 tives of the present invention are illustrated and com- Example m pared in the Falex test machine results given in Tables The dialkylated phenol product of Example 4 (358.4 l and .o grams) in 700 ml. of n-heptane was stirred with 36 ml. TABLE I of sulfur monochloride added drop-wise. The solution was heated under reflux for 2 hours with a nitrogen Falex Failure} purge. To the cooled (80C) product was added 500 Additive C0nc.. wtf/i pounds ml. of water with stirring. The heptane layer was sepa-. I

rated, washed with water (twice at 600 ml.), and dried Sim le 5 T with Na SO Evaporation gave the sulfurized phenol EW 1 1 (369 grams); percent CI, 0.11 percent. pi 3 4 100 The compositions of this invention can be used with Example 3 l a variety of greases and oils, that is, fluids of lubricating viscosity. fuels and functional fluids. Base oils include I such naturally Occurrmg OHS as nlphthenlc base '-'A neutral iiaraffinic base oil of viscosity about 480 SUS at 100F with 5 weight fi base, h lti b d i d b l b i ti OHS percent olpolyisuhutenyl sueeinimide and 0.1 weight percent 01 tercphthalic aeitl. Other lubricants include lubricating oils derived from coal products. synthetic oils s as p y of p py- It is evident from Tables I and n that the thio bis(- lene, butylenei aromatic hydrocarbons g dialkylphenol) additives wherein the substituents connated aromatic hydrocarbons, etc. Other illustrative tain a total of at least 10 carbon atoms are satisfactory oils are the esters of organic and inorganic acids, e.g. extreme pressure agents.

'fitBL'E n Compositions Additive. Wt 7r 1 2 3 4 I 5 6 7 8 Thin his(monoalkylphenol) 1.5 4,4-methylene bis(2.6-diterthutylphenol) 1.25 1.25 1.25 1.25 Example 2 1.0 2.0 1.0 1.5 2.0 Falex Shear I Load at failure. pounds 2650 900 4150 4250 4250 4250 4250 300 Base oil in a neutral paraffin oil of viscosity about 480 SUS at 100F with 6.25 weight percent of polyisobutcnyl succinimide. 0.1 weight percent of terephthalic acid and 1.0 weight percent of diparaffin polysu fide. A monolenapropenyl phenol.

carboxylates such as octylsebacate, etc. and silicates In additionto the additives described in this and phosphates, alkylene oxides and polymers thereof the lubncatmg Compositions y also contain may also be used. The base Oils may be used individw other lubricating oil and grease additives such as oilially or in combination, whenever miscible or made so g fil t .rust i r by the use ofmutual solvents. Oils oflubricating viscos- QXIdatlOH mhlbltorsi Corrosion mhlbltors. vlscosny ity are normally defined as those having viscosities at Index lmpmvmg agents dyes detergents dlspersams O I etc. Usually, for oils to be used in internal combustion 100 F m the rang: of 3540000 engines, the amount of these additives will range from about 0. 1-20 percent by weight, and more usually from about 0.5-l0 weight percent. The individual additives The additives of this invention will generally be present in lubricating oils in amounts of from about 0.5 to

20 weight percent of the total composition, more usumay vary in amounts f about 1( i h ally i m unt of from a ut l to 4 ght p nt f cent of the total composition. In concentrates, the the total composition. weight percent of these additives will usually range Evaluation from about 03-60 weight percent.

In order to demonstrate the enhanced effectiveness 1 claim:

of the compositions of this invention as additives in lu- A lubricating mPOSiti0n Comprising a major bricating oils and greases, a number of tests were caramount 9 on of lubricating- Viscosity and from ried out to determine their effectiveness as extreme to 20 we'ght percent of at least one Compound of the pressure agents. The additive compositions were evaluformula:

ated in the Falex shear test. In the Falex test, stationary OH OH vee-blocks are pressed on either side of a rotating steel I shaft by a nutcracker arrangement of lever arms. Test specimens are immersed in a tank of test lubricant which is at a known temperature. Loading is automatically increased until seizure occurs. The failure point is indicated by shearing of the pin holding the vertical wherein R is an alkyi group of from 10 to carbon 2. A lubricating oil composition according to claim atoms and n is an integer of from I to 4. 1 wherein is dodecyl.

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1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF AN OIL LUBRICATING VISCOSITY AND FROM 0.5 TO 20 WEIGHT PERCENT OF AT LEAST ONE COMPOUND OF THE FORMULA:
 2. A lubricating oil composition according to claim 1 wherein R'' is dodecyl. 